Electron Densities in the Solar Corona Measured Simultaneously in the Extreme Ultraviolet and Infrared

0547837 - ASÚ 2022 RIV US eng J - Journal Article
Dudík, Jaroslav - Del Zanna, G. - Rybák, J. - Lörinčík, Juraj - Dzifčáková, Elena - Mason, H. E. - Steven, T. - Galloy, M.
Electron Densities in the Solar Corona Measured Simultaneously in the Extreme Ultraviolet and Infrared.
Astrophysical Journal. Roč. 906, č. 2 (2021), č. článku 118. ISSN 0004-637X. E-ISSN 1538-4357
R&D Projects: GA ČR(CZ) GA18-09072S
Institutional support: RVO:67985815
Keywords : solar corona * solar coronal loops * solar electromagnetic emission
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 5.521, year: 2021
Method of publishing: Limited access
https://doi.org/10.3847/1538-4357/abcd91

Accurate measurements of electron density are critical for determination of the plasma properties in the solar corona. We compare the electron densities diagnosed from Fe xiii lines observed by the Extreme-Ultraviolet Imaging Spectrometer (EIS) onboard the Hinode mission with the near-infrared (NIR) measurements provided by the ground-based Coronal Multichannel Polarimeter (CoMP). To do that, the emissivity-ratio method based on all available observed lines of Fe xiii is used for both EIS and CoMP. The EIS diagnostics is further supplemented by the results from Fe xii lines. We find excellent agreement, within 10%, between the electron densities measured from both extreme-ultraviolet and NIR lines. In the five regions selected for detailed analysis, we obtain electron densities of log(N-e [cm(-3)]) = 8.2-8.6. Where available, the background subtraction has a significant impact on the diagnostics, especially on the NIR lines, where the loop contributes less than a quarter of the intensity measured along the line of sight. For the NIR lines, we find that the line center intensities are not affected by stray light within the instrument, and recommend using these for density diagnostics. The measurements of the Fe xiii NIR lines represent a viable method for density diagnostics using ground-based instrumentation.
Permanent Link: http://hdl.handle.net/11104/0323999